Sheet-metal evaporator



July 25, 1939.

D. P. HEATH SHEET-METAL EVAPORATOR Filed April 9, 1931 2 Sheets-Sheet 1IN'VENTOR M ly 1939- D. P. HEATH SHEET'METAL EVAPORATOR Filed April 9,1931 2 Sheets-Sheet 2 6 IQVENTO Patented July 25, 1939 PATENT OFFICESHEET-METAL EVAPORAT'OR Delos P. Heath, Detroit, Mich., assignor, by,

mesne assignments, to General Motors Corporation, a corporation ofDelaware Application April 9, 1931, Serial No. 528,847

8 Claims.

It is an object to provide a process of making a sheet metal evaporatorfrom a thin walled structure one of whose Walls is corrugated and formedinto a U-shape by a die in a single forming operation.

It is an object to provide a sheet metal evaporator enclosing a freezingchamber, which evaporator will comprise a minimum number of parts andwhich will allow a maximum economy in its complete manufacture by thestamping and the welding processes.

In the drawings:

Figure l is a front elevation of the outer shell of the evaporator afterthe forming operation.

Figure 2 is a side elevation of Figure 1, and also shows in dotted linesa modification of the header portion.

Figure 3 is a front elevation of the inner shell of the evaporator afterthe forming operation and also shows in dotted lines a modification ofthe portion of the sheet connecting the side walls.

Figure 4 is a front elevation of the assembled evaporator.

Figure 5 is a partial vertical section through Figure 4 at AA.

Figure 6 is a partial vertical section through Figure 4 at BB.

Figure '7 shows a modification of Figure 1 with flanges. 1

Figure 8 illustrates the side elevation of Figure 7.

Figure 9 shows the evaporator of Figure 7 assembled with an inner shell,a modification of Figure 3, to form the expansion chamber of a removableintegral refrigerating unit.

Figure 10 is a plan view of the .fianged outer shell shown in Figure 7assembled with its flanged inner shell.

Fig, 11 is a detail of welding flanged ends; and Fig. 12 is a modifiedview ofthe evaporator disclosed in Fig. 9 showing a pipe secured to thewalls of the structure and providing communication between the headersformed at the top of the evaporator,

closed an evaporator of general construction illustrated in Figure 9.

, Numeral I indicates a thin metallic sheet preferably of a steelsuitable for deep drawing and which may be protected against corrosion.A plurality of corrugations, 2, may be formed with the header portions,4 and 5, communicating therewith, in one stamping operation at the sametime the sheet is formed into a U-shaped structure as shown in Figure 1.3 indicates flat portions of I between the corrugations. These flatportions lie in substantially the same line with each other and with theperipheries I.

The inner shell 8, Figure 3, being formed in a U-shape similar to Figurel in section, the peripheries I on two sides of the shells I and 8 maybe assembled continuously contiguous at the front and back ofassemblies, Figs. 4 and 9.

As a modification theheader portion of sheets I and 8 may be formed astrue cylindrical shapes extending to the front and back edges asindicated by the dotted lines in Figure 2. However, with thismodification, as in my Patent Number 1,726,486 dated August 27-, 1929,it will be necessary to provide additional closure means at the ends ofthe header. The side walls of the shells I and 8 may be connected by aplain surface portion as shown in Figure 9, or by an arcuate surfaceportion as shown in Figures 1 and 3. It is also possible to indent ininitially forming the connecting portion of 8 between the side walls, toprovide additional strength and volume as shown dotted in Figures 3 and4.

After I and 8 are formed and super-imposed together the contiguousportions 3 and 1 of I are welded to 8 by the spot welding orseam-welding process. It may also be desirable to fasten thesecontiguous portions together by other means, such as, copper brazing;

To obtain the evaporator of Figure 4, the short portion, III, of theWelded assembly of sheets I and 8, is formed inwardly until the edges ofthe walls meet to form a small semi-cylindrical header, 4. The bottomedges of the inner sheet 8 and the outer sheet, I, are welded togetherto form a i Figure 9 shows the sheet metal tray shelf I3, which may beeither fixed to or removable from the side walls, but it is preferablyin close heat conducting contact with the walls of shell 8 to permit theremoval of heat from I2 at a rapid rate.

Numeral I4 designates flanges formed outwardly at the upper ends ofshells I and 8 as shown in Figures 7, 8, 9, 10, to provide sealing meansand if desired supporting means for the two shells. I5, are slotsstamped out of I4 to conveniently receive screws, rivets, or bolts, II,which may removably or permanently fasten the evaporator to theinsulated removable refrigerating machine base, l6, as shown in Figure9. In this latter figure the numeral I 8, indicates a condensing unitmounted on I 6, and operatively connected to the sheet metal evaporator,formed by shells I and 8, and to the high pressure float valve, I9."I'his cooling apparatus may be inserted in an opening in therefrigerator, 2| or removedtherefrom as an integral unit.

Member 28 is a tube leading refrigerant liquid from the float valve I9through the inlet II of the flange I4 at the top of shell 8, to thebottom of the evaporator.

' In the modified showing, Fig. 12, of the evaporator structuredisclosed in Fig. 9, 22 designates a refrigerant header pipe that may bewelded gas tight near the top of the side walls of shell 8, Figure 9, toprovide free fluid flow and additional gas and liquid space between theheaders, 4. If this pipe 22 is built into the evaporator as shown inFig. 12 is also eliminates the necessity of twoevaporator outlets andserves to stiffen the structure.

23 is the suction pipe connecting the condensing unit I8 to the outletopening II in the flange I 4 of the sheet 8.

In operation refrigerant gas occupying space between sheets I and 8 iswithdrawn by the condensing unit I8 through suction pipe 23, andcondensed to a liquid. Liquid refrigerant accumulating in I9 raises thefloat to admit the liquid through inlet tube 28, to the bottom of theexpansion chamber. This liquid freely cire culates through thecorrugations 2, and the headers 4 and 5, in contact with the shells Iand 8, to receive refrigerator heat energy through these metallic walls.When the liquid becomes superheated gas bubbles form and rapidly rise tothe headers 4 of Figure 9, and the header 5, of Figure 4.

In both the evaporators shown, the refrigerant liquid and gas may freelyflow at the bottom of the evaporator between the side walls, however, inFigure 11 is shown a modification of the method of joining the bottomends of the two sheets I and 8. Whereas, in Figure 4 these sheets form asemi-cylindrical header 4, in a modification, flanges are formed on theends of the shells in Figures 1 and 3 as illustrated in Figure 7. Theseflanges are welded together gas tight, as shown in Figure 9, and afterforming the portions III the flanges are abutted and welded together.

Although Figures 4 and 9 show the side walls of shells I and 8 formed atright angles to the portions I 8 and 6 respectively, it is entirelypracticable to assemble shells I and 8 by the welding process and to usethem as a complete evaporator while retaining the slight angle of draftrequired in the forming operation.

I have described a particular use of the invention in the, manufactureof evaporators for refrigerators, but I do not wish to limit the scopeof the invention to this use as it may be employed in forming corrugatedwall structure pressure vessels for many other purposes.

I claim:

1. A cooling unit for mechanical refrigeration comprising, an inner onepiece shell bent to form walls enclosing a horizontal ice freezingchamber or chambers, an outer one piece shell having an arcuate gasliquid header portion and side walls extending therefrom along the top,the sides and the bottom of the said inner shell freezing chamber wallsand terminating with arcuate liquid header portions at its ends, saidouter shell header portions forming with portions of tus comprising, aninner one-piece shell bent to form walls of a horizontal freezingchamber or chambers, an outer one-piece shell having a portion bulgedoutwardly of other portions thereof and having said other portionsextending adja cent the wall-forming portions of the inner shell toprovide double walls for said freezing chamber or chambers, theextending portions of said outer shell terminating with outwardly bulgedportions, said first named outwardly bulged por-' I tion of said outershell forming with a portion of the inner shell a header or manifold atthe top of the freezing chamber, the end portions of the inner shell andthe outwardly bulged portions at the terminations of the outer shellbeing secured together and forming a second header or manifold at thebottom of the freezing chamher, and the portions of said outer shellextend ing from the first named header or manifold adjacent thewall-forming portions of the inner shell being secured to said innershell at certain points and spaced therefrom at certain other points toprovide refrigerant passages between the shells, said passagesconnecting said first named header or manifold with said second namedheader or manifold.

3. A refrigerant containing evaporator includ-.

ing flat sheets of metal disposed adjacent each other and weldedtogether, said assembled sheets forming two parallel vertical walls anda connecting bottom wall to provide an ice freezing container,corrugations formed in one of the sheets to provide a series ofvertically-extending refrigerant passageways, headers formed at theupper ends of each of the parallel wallsand connectingvertically-extending refrigerant passageways, refrigerant outlet meansfrom said headers, an auxiliary header extending transversely of thepassages and connecting the bottoms of passageways of both verticalwalls, and an inlet conduit for conveying refrigerant to the evaporator,said inlet conduit extending into one of said vertical passageways nearthe top thereof to convey refrigerant downwardly to the auxiliary headerand from thence upwardly through a plurality of the passageways inbothvertical walls to said upper headers and from thence to said outletmeans.

4. An evaporator for a refrigerating machine comprising complementarysheet metal portions at least one of which portions has an indentationformed therein providing a header, a plurality of refrigerantcirculatory passages formed between said sheet metal portions and havingtheir one ends communicating with said header below a normal liquidlevel to be maintained therein, the other ends of said passages being inopen communication with each other at a point remote from said header,and means for discharging incoming liquid refrigerant to said evaporatorinto only a predetermined number of the total number of said pluralityof refrigerant passages remote from and intermediate the point ofcommunication of said other ends of said passages and the header, theremainder of said plurality of refrigerant passages providingunobstructed paths of flow for the free circulation of refrigerantbetween said header and the point of communication of the said otherends of said passages.

5. An evaporator for a refrigerating machine comprising complementaryU-shaped sheet metal portions, at least one of said sheet metal portionshaving indentations formed therein providing a header adjacent the topof each leg of the U and a plurality of depending refrigerantcirculatory passages communicating with said headers below a normalliquid level to be maintained therein, and means for dischargingincoming liquid refrigerant to said evaporator into only a predeterminednumber of the total number of said plurality ofrefri'gerant passagesremote from and between said headers, the remainder of said plurality ofrefrigerant passages providing unobstructed paths of flow for the freecirculation of refrigerant between said headers.

6. An evaporator for a refrigerating machine comprising complementaryU-shaped sheet metal portions, at least one of said sheet metal portionshaving indentations formed therein providing a header adjacent the topof each leg of the U and a plurality of depending refrigerantcirculatory passages communicating with said headers below a normalliquid level to be maintained therein, and means for dischargingincoming liquid refrigerant to said evaporator into only a predeterminednumber of the total numher of said plurality of refrigerant passagesincluding a refrigerant conduit entering the wall of one of said headersand passing downwardly through one of said passages to a point remotefrom and between said headers, the remainder of said plurality ofrefrigerant passages providing unobstructed paths of flow for the freecirculation of refrigerant between said headers.

7. An evaporator for a refrigerating machine including a pair of headersformed between complementary sheet metal portions, means including aplurality of refrigerant passages depending from and communicating withsaid headers below a normal liquid level to be maintained therein forcirculating liquid refrigerant supplied to said evaporator, a conduitconnecting said headers above the liquid levels therein, and means fordischarging incoming liquid refrigerant to said evaporator into only apredetermined number of the total number of said plurality ofrefrigerant passages remote from and between said headers, the remainderof said plurality of refrigerant passages providing unobstructed pathsof flow for the free circulation of refrigerant between said headers.

8. An evaporator for' a refrigerating machine comprising complementaryU-shaped sheet metal portions, at least one of said sheet -metalportions having indentations formed therein providing a header adjacentthe top of each leg of the U and a plurality of depending refrigerantcirculatory passages communicating with said headers below a normalliquid level to be maintained therein, a tube connecting said headersabove the liquid levels therein, means for discharging incoming liquidrefrigerant to said evaporator into only a predetermined number of thetotal number of said plurality of refrigerant passages including arefrigerant conduit entering the wall of one of said headers and passingdownwardly through one of said passages to a point remote from andbetween said headers, the remainder of said plurality of passagesproviding unobstructed paths of flow for the free circulation ifrefrigerant between said headers, and means'for removing vaporizedrefrigerant from the other of said headers.

DELOS P. HEATH.

